diff --git a/docs/topics/forms/modelforms.txt b/docs/topics/forms/modelforms.txt
index b660308891..4a44de2d2a 100644
--- a/docs/topics/forms/modelforms.txt
+++ b/docs/topics/forms/modelforms.txt
@@ -861,7 +861,8 @@ As with regular formsets, it's possible to :ref:`specify initial data
 parameter when instantiating the model formset class returned by
 :func:`~django.forms.models.modelformset_factory`. However, with model
 formsets, the initial values only apply to extra forms, those that aren't
-attached to an existing model instance.
+attached to an existing model instance. If the extra forms with initial data
+aren't changed by the user, they won't be validated or saved.
 
 .. _saving-objects-in-the-formset: